1. Field
The invention relates to wireless communications. More particularly, the invention relates to methods and apparatus for improving power efficiency and latency of mobile devices using an external timing source.
2. Background
Wireless communications continues to grow in demand and has become an integral part of both personal and business communications. Wireless communications allow users to transmit and receive data from most anywhere using wireless networks and mobile devices such as laptops, cellular devices, iPhones, BlackBerrys, etc.
Wireless fidelity (WiFi) describes the wireless networks that adhere to the specifications developed by the Institute of Electrical and Electronic Engineers (IEEE) for wireless local area networks (LAN). WiFi devices are certified to be interoperable with other certified WiFi devices using the 802.11 standard of the IEEE. These WiFi devices allow over-the-air interfaces in order to create a wireless network for facilitating data transfer.
In some instances, the data transfer can be facilitated by running WiFi applications (e.g., exchange peer discovery information, exchange traffic routing information, connection setup requests, and traffic monitoring) on the mobiles devices. For example, the WiFi applications can be run on the mobile devices when the mobile devices are in a passive mode; however, WiFi applications consume large amounts of current, thus impacting the standby time of the mobile devices and even making it infeasible to run certain WiFi applications on the mobile devices. Some power saving features are currently available on mobile devices, however, most are inefficient at running these WiFi applications.
In addition, the asynchronous nature of WiFi further impacts the latency and the power efficiency of mobile devices. That is, transmissions and receptions using WiFi are not synchronized but rather are performed in an asynchronous manner. For example, a WiFi transmitter may try to communicate with a WiFi receiver at a random time and if the WiFi receiver is not ready to communicate at the random time or is surrounded by other WiFi transmitters trying to communicate with the WiFi receiver, the WiFi receiver is unable to receive the data correctly in which case the WiFi transmitter may decide to back-off and transmit at a later time (e.g., 10 milliseconds later). This example illustrates the inherent latencies in WiFi communications. Furthermore, power inefficiencies are also increased for the WiFi transmitter and the WiFi receiver.
Therefore, it has been recognized by those skilled in the art that a need exists for methods and apparatus for improving power efficiency and latency of mobile devices.